Electric water pump

ABSTRACT

An electric water pump includes a pump cover having an inlet through which coolant flows; a stator chamber having a stator generating a magnetic field according to a control signal; a rotor chamber having a rotor rotating according to the magnetic field generated by the stator; a separation wall configured to separate the stator chamber from the rotor chamber; a shaft having a central axis, fixed to the rotor so as to rotate together with the rotor about the central axis thereof; and an impeller fixed to a front portion of the shaft so as to rotate together with the shaft, the impeller pressurizing a coolant having flowed in through the inlet, wherein at least one wing portion is formed on a part of the shaft to increase a flow of the coolant.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to Korean PatentApplication No. 10-2015-0046992, filed in the Korean IntellectualProperty Office on Apr. 2, 2015, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electric water pump. Moreparticularly, the present disclosure relates an electric water pumphaving a wing portion in order to increase a flow of a coolant.

BACKGROUND

Generally, a water pump circulates coolant to an engine and a heater tocool the engine and heat a cabin. The coolant flowing out from the waterpump circulates through and exchanges heat with the engine, the heaterand/or the radiator, and flows back in the water pump.

The water pump is connected to a pulley fixed to a crankshaft of theengine and is driven according to the rotation of the crankshaft (i.e.,the rotation of the engine). Therefore, the coolant amount flowing fromthe mechanical water pump is determined according to rotational speed ofthe engine. However, the coolant amount required in the heater andradiator is a specific value regardless of the rotational speed of theengine. Therefore, the heater and the radiator do not properly operatewhere the engine speed is slow. In order to operate the heater and theradiator normally, the engine speed must be increased. However, if theengine speed is increased, the fuel consumption of a vehicle is alsoincreased.

The electric water pump is driven by a motor controlled by a controlapparatus. The electric water pump can determine the coolant amountregardless of the rotational speed, and can reduce required power by60-70% as compared with the mechanical water pump. Moreover, theelectric water pump is advantageous in view of packaging over themechanical water pump.

A DC motor is normally used in the electric water pump, particularly aBLDC(Brushless DC) motor. A controller which can control the BLDC motoris provided with the motor, and an electric circuit is built-in theinside of the controller. As the controller is operated, heat isgenerated in an electric device. Therefore, sufficient cooling thereinis required in order to prevent overheating

The BLDC motor has a coolant line between a stator wound with a coil anda rotor with a permanent magnet. However, a space between the stator andthe rotor should be within a few millimeters so as to function. Becauseof such a space constraint, the amount of coolant that flows between thestator and the rotor is not sufficient, and the coolant flow is notsmooth. Therefore, the heat produced in the electric water pump isdifficult to remove therefrom.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the disclosure andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE DISCLOSURE

The present disclosure has been made in an effort to provide an electricwater pump to increase a flow of a coolant. An exemplary embodiment ofthe present disclosure provides an electric water pump having a wingportion in order to increase a flow of a coolant and improve coolingperformance.

The electric water pump may include a pump cover having an inlet throughwhich coolant flows; a stator chamber having a stator generating amagnetic field according to a control signal; a rotor chamber having arotor rotated by the magnetic field generated by the stator; aseparation wall configured to separate the stator chamber from the rotorchamber; a shaft having a central axis, the shaft fixed to the rotor soas to rotate together with the rotor about the central axis; and animpeller fixed to a front portion of the shaft so as to rotate togetherwith the shaft, the impeller pressurizing the coolant flowing throughthe inlet, wherein at least one wing portion is formed on a part of theshaft so as to increase a flow of the coolant. The wing portion may beformed at a front or a rear end portion of the shaft. The shaft maycomprise a trunk portion extended through a center of the separationwall along the central axis; and an extending portion having a smallerdiameter than the trunk portion and extended from a front portion or arear portion of the trunk portion along the central axis, wherein thewing portion has at least one rotatable blade protruding from the frontportion or the rear portion of the trunk portion so as to increase theflow of the coolant. The wing portion may have at least one rotatableblade protruding outwardly in a radial direction from an exteriorcircumferential portion of the trunk portion or the extending portion soas to increase the flow of the coolant. The wing portion may have atapered shape which becomes narrow gradually in a radial direction, andhave a sharp end portion. The wing portion may comprise: at least onelong blade configured to protrude from the exterior circumferentialportion in a radially outward direction; and at least one short bladeconfigured to protrude from the exterior circumferential portion in aradially outward direction, the at least one short blade having asmaller radius of rotation than the long blade. The at least one longblade and the at least one short blade mat be alternately arranged. Theelectric water pump may further comprise a body having the statorchamber and the rotor chamber; and a driver case mounted at a rear endof the body, having a fixing member protruding in a forward direction soas to fix the separation wall thereto. A separation space may be formedbetween a rear surface of the separation wall and a front surface of thedriver case. A front end portion of the fixing member may be disposedapart from the rear surface of the separation wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an electric water pump according toan exemplary embodiment of the present disclosure.

FIG. 2 is an enlarged schematic diagram of a portion A.

FIG. 3 is a perspective view of a wing portion that is applied to anelectric water pump according to an exemplary embodiment of the presentdisclosure.

FIG. 4 is a cross-sectional view of a wing portion that is applied to anelectric water pump according to an exemplary embodiment of the presentdisclosure.

DETAILED DESCRIPTION

An exemplary embodiment of the present disclosure will hereinafter bedescribed in detail with reference to the accompanying drawings.

Throughout this specification and the claims which follow, In addition,unless explicitly described to the contrary, the word “comprise” andvariations such as “comprises” or “comprising” will be understood toimply the inclusion of stated elements but not the exclusion of anyother elements.

For better comprehension and ease of description, a direction which isleft side of a drawing is referred to as “a front surface”, “a frontportion”, or “frontward”, and the opposite direction is referred to as“a rear side”, “a rear portion” or “rearward”.

Throughout the specification, components denoted by the same referencenumerals are the same or similar components.

FIG. 1 is a cross-sectional view of an electric water pump according toan exemplary embodiment of the present disclosure.

An electric water pump 1 according to an exemplary embodiment of thepresent disclosure includes a pump cover 10, a body 30, a driver case 50and a driver cover 70.

The body 30 is engaged to a rear end of the pump cover 10 so as to forma volute chamber 14 and a rotor chamber 35. The driver case 50 isengaged to a rear end of the body 30 to form a stator chamber 45, and adriver cover 70 is engaged to a rear end of the driver case 50 to form adriver chamber 85.

In addition, an impeller 17 is mounted in the volute chamber 14, and therotor 37 fixed to a shaft 100 is mounted in the rotor chamber 35. Astator 47 is mounted in the stator chamber 45, and a driver 80 ismounted in the driver chamber 85. The shaft 100 has a central axis x,and the rotor 37, as well as the shaft 100, rotate about the centralaxis x. The stator 47 is disposed coaxially with the central axis x ofthe shaft 100.

The pump cover 10 is provided with an inlet 12 at a front end portionthereof and an outlet 15 at a side portion thereof. The coolant flows inthe electric water pump 1 through the inlet 12, and the pressurizedcoolant in the electric water pump 1 flows out through the outlet 15. Aslanted surface 3 is formed at a rear end portion 20 of the inlet 12 ofthe pump 1, and a rear end portion 20 is extended rearward from slantedsurface 3. The rear end portion 20 of the pump cover 10 covers amounting portion 32 of the body 30 by fixing means such as a bolt B. Theslanted surface 3 is slanted with reference to the central axis x of theshaft 100.

The volute chamber 14 for pressurizing the coolant is formed in the pumpcover 10, and the impeller 17 for pressurizing the coolant through theoutlet 15 is mounted in the volute chamber 14. The impeller 17 is fixedto a front end portion of the shaft 100 and rotates together with theshaft 100. For this purpose, a bolt hole 29 is formed at a middleportion of the impeller 17 and a thread is formed at an interiorcircumference of the bolt hole 29. An impeller bolt 28 inserted in thebolt hole 29 is threaded to the front end portion of the shaft 100 suchthat the impeller 17 is fixed to the shaft 100. A washer w may beinterposed between the impeller 17 and the impeller bolt 28.

The coolant flowing into the water pump 1 may be smoothly guided andperformance of the water pump 1 may be improved as a consequence ofdisposing the centers of the impeller 17 and the rotor 37 (rotatingelements of the water pump 1) and a center of the stator 47 (a fixedelement of the water pump 1) on the central axis x.

In addition, the impeller 17 is divided into a plurality of regions by aplurality of blades 18. The coolant flowing into the plurality ofregions is pressurized by rotation of the impeller 17. Meanwhile, asmarked by the arrow in FIG. 1, the coolant flowing in the inlet 12 isdelivered into the rotor chamber 35 via the impeller 17.

The body 30 has a hollow cylindrical shape that is opens to the rear,and is engaged to the rear end portion of the pump cover 10. The body 30includes an adapter 25, a separation wall 90, the stator chamber 45 andthe rotor chamber 35.

The adapter 25 supports the separation wall 90 at a rear end portion. Abearing mounting portion 26 protrudes rearward from the adapter 25, anda bearing is interposed between the bearing mounting portion 26 and theshaft 100 in order to make the shaft 100 smoothly rotate and to preventthe shaft 100 from being inclined.

A penetration hole 27 is formed at a middle portion of the adapter 25such that the front end portion of the shaft 100 protrudes into volutechamber 14 through the penetration hole 27. The impeller 17 is fixed toa front portion of the shaft 100. It is described in this specificationthat the impeller 17 is fixed to the shaft 100 by the impeller bolt 28.However, the impeller 17 may also be press-fitted to an exteriorcircumference of the shaft 100.

A connecting hole 34 is formed in the adapter 25 radially outward of thebearing mounting portion 26. Therefore, as marked by the arrow, thecoolant flowing through the impeller 17 is delivered into the rotorchamber 35 through the connecting hole 34. In addition, the coolantflowing in the rotor chamber 35 passes through a gap 5 formed betweenthe separation wall 90 and the rotor 37. Heat generated at the shaft100, the rotor 37 and the stator 47 by operation of the water pump 1 iscooled by the coolant flow. Therefore, the durability of the water pump1 may be improved. Further, floating materials in the coolant areprevented from accumulating in the rotor chamber 35.

The separation wall 90 is formed in a cup-shaped opened in the impeller17 direction, and is interposed between the stator 47 and the rotor 37.The stator 47 is disposed outwardly in a radial direction, and the rotor37 is disposed inwardly in a radial direction.

The separation wall 90 includes a front surface 91 forming a volutechamber 14 between the pump cover 10 and the front surface 91. The frontsurface 91 of the separation wall 90 is provided with a first partition92, and a second partition 93 formed sequentially from an exteriorcircumference to a center thereof.

The first partition 92 is engaged to the rear end portion 20 of the pumpcover 10. Sealing means such as an O-ring O may be interposed betweenthe first partition and the rear end portion 20 to prevent leakage ofthe coolant from the volute chamber 14.

The second partition 93 protrudes rearward from the front surface 91,and defines a boundary between the stator chamber 45 and the rotorchamber 35. The stator 47 is mounted outwardly in the radial directionof the second partition 93.

The stator chamber 45 is formed at a radially outer portion of theseparation wall 90, and the stator 47 is mounted in the stator chamber45. The stator 47 is fixed to the body 30, directly or indirectly, andgenerates a magnetic field according to a control signal that isobtained from an outside source.

The rotor chamber 35 is formed at a radially inner portion of theseparation wall 90, and a supporting portion 60, rotor 37 and shaft 100are mounted in the rotor chamber 35.

The supporting portion 60 is made of an elastic rubber material, andrelieves the thrust of the shaft 100 exerted to the bearing 31.Meanwhile, when the supporting portion 60 is connected with the bearing31 directly, a rotational friction may be generated between the bearing31 and the supporting portion 60 of the rubber material, and maydeteriorate performance of the water pump 1. Therefore, a thrust ring 65is mounted between the bearing 31 and the supporting portion 60, and therotation friction may be reduced.

The rotor 37 is fixed to the external circumference portion of the shaft100 in a cylinder shape by, for example, a press-fit or weld. Thepermanent magnet is mounted at the rotor 37, and the rotor 37 rotates bythe magnetic field generated in the stator 47.

Referring to FIG. 2 to FIG. 4, shaft 100 will be described in detailbelow.

FIG. 2 is an enlarged schematic diagram of a portion A, FIG. 3 is aperspective view of a wing portion that is applied to an electric waterpump according to an exemplary embodiment of the present disclosure, andFIG. 4 is a cross-sectional view of a wing portion that is applied to anelectric water pump according to an exemplary embodiment of the presentdisclosure.

As shown in FIG. 2 to FIG. 4, shaft 100 includes a trunk portion 105, anextending portion 120 and a wing portion 110. The trunk portion 105 isextended in a center of the separation wall 90 along the central axis x.The extending portion 120 is extended from the trunk portion 105 forwardor rearward in an axial direction having a smaller radius than the trunkportion 105.

At least one or more wing portions 110 may be provided on a front orrear portion of the shaft 100. If the shaft 100 rotates, the wingportion 110 rotates together with it. The wing portion 110 is formed ina wing shape so as to create more flow of a fluid when the shaft 100rotates. In other words, the wing portion 110 may be extended in anaxial direction from the front or rear side of the trunk portion 105,and may be extended from an exterior circumference of the extendingportion 120 in a radially outward direction.

The wing portion 110 is formed as a common blade, and it is well knownto a person of ordinary skill in the art. Therefore, as the wing portion110 rotates with rotation of the shaft 100, a kinetic energy generatedby the wing portion 110 increases a flow of the fluid. The water pump 1may be cooled quickly by the coolant passing through the gap 5 betweenthe shaft 100 and the separation wall 90.

Meanwhile, the wing portion 110 is in a shape integrally formed at therear end portion of the shaft 100 in this specification, but the presentdisclosure is not limited thereto. The wing portion 110 may also bedisposed or formed at any part of the shaft 100, including the front endportion of the shaft 100 by which coolant flows.

According to an exemplary embodiment of the present disclosure, as shownin FIG. 3 to FIG. 4, the wing portion 110 is provided to protrude from alateral surface of the trunk portion 105 or the exterior circumferenceof the extending portion 120. The wing portion 110 includes at least onelong blade 111 and at least one short blade 112.

Referring to FIG. 4, each long blade 111 is formed at the exteriorcircumference of the extending portion 120 and is more extended than theshort blade 112 in a radially outward direction. Also, each short blade112 may be disposed between each long blade 111.

Therefore, when the shaft 100 rotates, a change of the flow may behigher than that caused when forming the long blade 111 and the shortblade 112 as a same size. Thus, cooling performance may be improved.

While each long blade 111 and each short blade 112 are extended in aradially outward direction, a thickness of each blade may be thinned.For example, the long and short blades 111, 112 may be in a taperedshape. The end portions of the long and short blades 111, 112 may beformed as a sharp shape. Therefore, lateral surfaces of each long blade111 and each short blade 112 may be formed to be slanted, and the shaft100 may rotate in order to increase the flow of coolant while minimallybeing affected by a torque resistance.

The driver case 50 is engaged to a rear end of the body 30 to form thestator chamber 45. As shown in FIG. 2, the driver case 50 includes afirst fixing member 51 and a second fixing member 52 which protrudeforward in order to support the separation wall 90. A part of theseparation wall 90 may be inserted between the first fixing member 51and the second fixing member 52, and fixed therebetween.

Separation spaces D1, D2, and D3 may be formed between a rear surface ofthe separation wall 90 and a front surface of the driver case 50. Eachseparation space D1, D2, and D3 may be formed between the rear endsurface of the separation wall 90 and the front end surface of thedriver case 50, between the rear surface of the separation wall 90 and afront end of the first fixing member 51, and between the rear surface ofthe separation wall 90 and a front end of the second fixing member 52.These separation spaces D1, D2, and D3 prevent a vibration by the thrustof the shaft 100 from being exerted to driver 80 disposed at a rear ofthe driver case 50.

The driver cover 70 is formed from the driver case 50 in an axialdirection, and is in a disk shape. The driver cover 70 is engaged to thedriver case 50 by fixing means such as a bolt so as to form a driverchamber 85. Sealing means such as a O-ring O may be interposed radiallyoutward of the driver cover 70 to prevent foreign substances, such asdust, from entering the driver chamber 85.

The driver 80 controlling operations of the water pump 1 is mounted inthe driver chamber 85. The driver 80 includes microprocessors and aprinted circuit board (PCB). The driver 80 is electrically connected toa controller (not shown) disposed at an exterior of the electric waterpump 1 and receives a control signal from the controller.

As described above, according to an exemplary embodiment of the presentdisclosure, the shaft 100 rotates with a rotor 37 and is provided withthe wing portion 110. Therefore, a flow of a coolant passing through thegap 5 between the shaft 100 and the separation wall 90 is increased. Asa result, the electric water pump 1 may have a high cooling efficiencyand performance level.

While this disclosure has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the disclosure is not limited to the disclosedembodiments. On the contrary, it is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An electric water pump comprising: a pump coverhaving an inlet through which a coolant flows; a stator chamber having astator that generates a magnetic field according to a control signal; arotor chamber having a rotor rotated by the magnetic field; a separationwall configured to separate the stator chamber from the rotor chamber; ashaft having a central axis, the shaft fixed to the rotor so as torotate together with the rotor about the central axis; and an impellerfixed to a front portion of the shaft that rotates together with theshaft and pressurizes the coolant flowing through the inlet, wherein atleast one wing portion is formed on a part of the shaft to increase aflow of the coolant.
 2. The electric water pump of claim 1, wherein thewing portion is formed at a front or a rear end portion of the shaft. 3.The electric water pump of claim 2, wherein the shaft comprises: a trunkportion extended through a center of the separation wall along thecentral axis; and an extending portion having a smaller diameter thanthe trunk portion and extended from a front portion or a rear portion ofthe trunk portion along the central axis, wherein the wing portion hasat least one rotatable blade protruding from the front portion or therear portion of the trunk portion so as to increase the flow of thecoolant.
 4. The electric water pump of claim 2, wherein the wing portionhas at least one rotatable blade protruding outwardly in a radialdirection from an exterior circumferential portion of the trunk portionor the extending portion to increase the flow of the coolant.
 5. Theelectric water pump of claim 4, wherein the wing portion has a taperedshape which becomes narrow gradually in a radial direction, and has asharp end portion.
 6. The electric water pump of claim 4, wherein thewing portion comprises: at least one long blade configured to protrudefrom the exterior circumferential portion in a radially outwarddirection; and at least one short blade configured to protrude from theexterior circumferential portion in a radially outward direction, the atleast one short blade having a smaller radius of rotation than the longblade.
 7. The electric water pump of claim 6, wherein the at least onelong blade and the at least one short blade are alternately arranged. 8.The electric water pump of claim 4, further comprising: a body havingthe stator chamber and the rotor chamber; and a driver case mounted at arear end of the body, having a fixing member protruding in a forwarddirection to fix the separation wall thereto.
 9. The electric water pumpof claim 8, wherein a separation space is formed between a rear surfaceof the separation wall and a front surface of the driver case.
 10. Theelectric water pump of claim 9, wherein a front end portion of thefixing member is disposed apart from the rear surface of the separationwall.